The goal of the present proposal is to increase our understanding of the role played by kinins as mediators of human allergic reactions. Using a recently developed model of nasal challenge, we have obtained data which demonstrate clearly, for the first time, kinin generation during a local allergic reaction in vivo. Preliminary evidence indicates that kinins are also generated during late phase reactions to antigen challenge and, in vasomotor rhinitis sufferers, upon challenge with cold air. In all cases kinin generation correlates with the production of mast cell/basophil mediators and with the onset of clinical symptoms. We intend to utilize this model to elucidate the mechanism(s) of kinin formation during allergic reactions, focussing particularly on the role of kininogenases produced by mast cells and basophils in kinin generation. Highly purified mast cells and basophils will be used to biochemically characterize these proteases sufficiently to enable their identification in samples obtained during allergic reactions in vivo. The mast cell protease will also be purified to homogeneity and a monospecific antiserum will be produced and used to establish a radio-immunoassay for this enzymes. In addition, purified mast cells and basophils will be used to study the pharmacologic control of kininogenase release from these cells. The ability to identify and measure the mast cell and basophil kininogenases will be used together with a comprehensive range of specific assays for plasma kallikrein, glandular kallikrein, high molecular weight kininogen and total kininogen to elucidate the mechanisms of kinin formation during early and late reactions as well as those caused by cold air. By studying the effects of drugs affecting mast cell and/or basophil release (as well as drugs inhibiting the actions of selected mast cell/basophil mediators) on kinin production and on the levels of each of the enzyme and substrates listed above, we will be able to evaluate the role of each enzyme in kinin production. Increased understanding of the role of kinins in allergic reactions, gained as a result of the present studies, may clarify the rationale required for the development of new, more effective drugs to combat allergic diseases in man.